U.S. patent number 6,138,032 [Application Number 08/864,518] was granted by the patent office on 2000-10-24 for method and apparatus for dynamically adjusting a battery saving interval in a messaging system.
This patent grant is currently assigned to Motorola, Inc.. Invention is credited to Alain Charles Louis Briancon, Thomas Victor D'Amico, Jheroen Pieter Dorenbosch, Steven Jeffrey Goldberg, Thomas Casey Hill, Jyh-Han Lin, Samir Sawaya, Terence Edward Sumner, Zhonghe Wang.
United States Patent |
6,138,032 |
Hill , et al. |
October 24, 2000 |
Method and apparatus for dynamically adjusting a battery saving
interval in a messaging system
Abstract
A battery saving interval utilized for communicating with a
portable subscriber unit (122) in a radio communication system is
dynamically adjusted. An occurrence of a predetermined triggering
event associated with the portable subscriber unit is observed
(504), and the battery saving interval utilized for communicating
with the portable subscriber unit is adjusted (506) in response to
the predetermined triggering event, while battery saving intervals
of other portable subscriber units in the system are left
unchanged.
Inventors: |
Hill; Thomas Casey (Trophy
Club, TX), D'Amico; Thomas Victor (Boca Raton, FL),
Briancon; Alain Charles Louis (Southlake, TX), Lin;
Jyh-Han (Keller, TX), Sawaya; Samir (San Diego, CA),
Goldberg; Steven Jeffrey (Fort Worth, TX), Wang; Zhonghe
(Lake Worth, FL), Dorenbosch; Jheroen Pieter (Paradise,
TX), Sumner; Terence Edward (Azle, TX) |
Assignee: |
Motorola, Inc. (Schaumburg,
IL)
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Family
ID: |
27104444 |
Appl.
No.: |
08/864,518 |
Filed: |
May 28, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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689617 |
Aug 12, 1996 |
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Current U.S.
Class: |
455/517;
340/7.33; 340/7.21; 455/343.1 |
Current CPC
Class: |
H04W
52/0225 (20130101); Y02D 70/00 (20180101); Y02D
30/70 (20200801); H04W 88/022 (20130101) |
Current International
Class: |
H04Q
7/18 (20060101); H04Q 7/14 (20060101); H04B
007/00 () |
Field of
Search: |
;455/38.3,393,522,69
;370/95.1,95.2,95.3,311
;340/825.44,825.06,825.22,825.26,825.27 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hunter; Daniel S.
Assistant Examiner: Tran; Pablo N.
Attorney, Agent or Firm: Breeden; R. Louis
Parent Case Text
RELATED APPLICATIONS
This application is a continuation-in-part of application Ser. No.
08/689,617, filed Aug. 12, 1996 now abandoned by Hill et al.,
entitled "Method and Apparatus for Dynamically Adjusting a Battery
Saving Interval in a Messaging System."
Application Ser. No. 08/531,505 filed Sep. 21, 1995 by Eaton,
entitled "Method for Selecting Battery Saving Period in a Selective
Call Receiver."
Claims
What is claimed is:
1. A method of applying a dynamic adjustment to a battery saving
interval utilized for communicating with a portable subscriber unit
in a radio communication system which employs a protocol having a
transmission cycle comprising a plurality of frames, the method
comprising the steps of:
observing an occurrence of a predetermined triggering event
associated with the portable subscriber unit; and
adjusting a number of frames during which the portable subscriber
unit will battery save when next operating in a battery saving mode
in response to the predetermined triggering event, while leaving
battery saving intervals of other portable subscriber units in the
system unchanged, wherein said number of frames during which the
portable subscriber unit will battery save when next operating in a
battery saving mode is adjusted in response to at least one of:
whether a message type to be sent to the portable subscriber unit
is voice, as opposed to data;
an elapsed time being less than a predetermined amount, said
elapsed time being that between a prior message received by the
portable subscriber unit and a message currently queued for the
portable subscriber unit;
a priority level associated with the message;
detecting a transmission of a negative acknowledgement (NAK) from
the portable subscriber unit; and
communication requirements for running an application program in
the portable subscriber unit when the application program is
started and stopped.
2. The method of claim 1,
wherein the predetermined triggering event comprises a presence of
a message in queue for the portable subscriber unit, said message
being of a type selected from one of voice and data, and
wherein the adjusting step comprises the step of adjusting said
number of frames according to said type.
3. The method of claim 1, wherein the adjusting step comprises the
step of
adjusting said number of frames in response to an elapsed time
being less than a predetermined amount, said elapsed time being
that between a prior message received by the portable subscriber
unit and a message currently queued for the portable subscriber
unit.
4. The method of claim 1,
wherein the predetermined triggering event occurs in response to an
attempt to send a message to the portable subscriber unit, the
message having a priority, and
wherein the adjusting step comprises the step of
adjusting said number of frames in response to a priority level
associated with the message.
5. The method of claim 1,
wherein the radio communication system comprises a fixed portion
and the portable subscriber unit, and
wherein the observing and adjusting steps occur independently in
both the fixed portion and the portable subscriber unit based upon
similar information present in the fixed portion and in the
portable subscriber unit and without requiring a communication
between the fixed portion and the portable subscriber unit.
6. The method of claim 1,
wherein the predetermined triggering event is a starting or
stopping of an application program in the portable subscriber unit;
and
wherein the adjusting step comprises the step of adjusting said
number of frames in accordance with the communication requirements
for running the application program.
7. The method of claim 1,
wherein the battery saving interval has a nominal value before
applying the dynamic adjustment, and
wherein the observing step comprises the step of detecting a
transmission of a negative acknowledgment (NAK) from the portable
subscriber unit, and
wherein the adjusting step comprises the step of
shortening the battery saving interval in response to the NAK,
and
wherein the method further comprises the step of queuing a retry
message in response to the NAK, such that the retry message is
given transmission priority over non-retry messages in the
system.
8. The method of claim 1,
wherein the battery saving interval has a nominal value before
applying the dynamic adjustment, and
wherein the observing step comprises the step of detecting a
transmission of a negative acknowledgment (NAK) from the portable
subscriber unit, and
wherein the adjusting step comprises the step of
reducing the battery saving interval to a minimum possible value in
response to the NAK, and
wherein the method further comprises the step of transmitting a
Where aRe You (WRU) command to the portable subscriber unit in a
next available transmission frame.
9. A controller in a radio communication system for applying a
dynamic adjustment to a battery saving interval utilized for
communicating with a portable subscriber unit, the radio
communication system employing a protocol having a transmission
cycle comprising a plurality of frames, the controller
comprising:
a network interface for accepting messages from message
originators;
a processing system coupled to the network interface for processing
the messages; and
a transceiver interface coupled to the processing system for
transmitting the messages and for receiving acknowledgments to the
messages,
wherein the processing system is programmed to:
observe an occurrence of a predetermined triggering event
associated with the portable subscriber unit, and
adjust a number of frames during which the portable subscriber unit
will battery save when next operating in a battery saving mode in
response to the predetermined triggering event, while leaving
battery saving intervals of other portable subscriber units in the
system unchanged, wherein said number of frames during which the
portable subscriber unit will battery save when next operating in a
battery saving mode is adjusted in response to at least one of:
whether a message type to be sent to the portable subscriber unit
is voice, as opposed to data;
an elapsed time being less than a predetermined amount, said
elapsed time being that between a prior message received by the
portable subscriber unit and a message currently queued for the
portable subscriber unit;
a priority level associated with the message;
detecting a transmission of a negative acknowledgment (NAK) from
the portable subscriber unit; and
communication requirements for running an application program in
the portable subscriber unit when the application program is
started and stopped.
10. A portable subscriber unit in a radio communication system for
applying a dynamic adjustment to a battery saving interval utilized
for communicating with a fixed portion of the system, the radio
communication system employing a protocol having a transmission
cycle comprising a plurality of frames, the portable subscriber
unit comprising:
a receiver for receiving messages from the fixed portion;
a processing system coupled to the receiver for processing the
messages; and
a transmitter coupled to the processing system for acknowledging
the messages,
wherein the processing system is programmed to:
observe an occurrence of a predetermined triggering event
associated with the portable subscriber unit; and
adjust a number of frames during which the portable subscriber unit
will battery save when next operating in a battery saving mode in
response to the predetermined triggering event, while leaving
battery saving intervals of other portable subscriber units in the
system unchanged, wherein said number of frames during which the
portable subscriber unit will battery save when next operating in a
battery saving mode is adjusted in response to at least one of:
whether a message type to be sent to the portable subscriber unit
is voice, as opposed to data;
an elapsed time being less than a predetermined amount, said
elapsed time being that between a prior message received by the
portable subscriber unit and a message currently queued for the
portable subscriber unit;
a priority level associated with the message;
detecting a transmission of a negative acknowledgment (NAK) from
the portable subscriber unit; and
communication requirements for running an application program in
the portable subscriber unit when the application program is
started and stopped.
Description
FIELD OF THE INVENTION
This invention relates in general to radio communication systems,
and more specifically to a method and apparatus for dynamically
adjusting a battery saving interval in a messaging system.
BACKGROUND OF THE INVENTION
Battery saving techniques have become increasingly important in
modern messaging systems that employ battery powered portable
subscriber units. In general, such systems have transmitted
messages in a plurality of cyclical time slots. Each subscriber
unit has been assigned to a predetermined subset of the time slots
and thus can remain in a low-power, "battery saving" mode during
all time slots except the predetermined subset to which the
subscriber unit is assigned.
Motorola's well-known FLEX.TM. protocol is a good example. The
FLEX.TM. protocol utilizes a repeating transmission cycle
consisting of 128 frames every four minutes. Each subscriber unit
is pre-programmed by a "pager collapse" value between zero and
seven to monitor every frame, every other frame, every fourth
frame, every eighth frame, every sixteenth frame, every 32nd frame,
every 64th frame, or every 128th frame, respectively. For best
battery life, the subscriber unit is pre-programmed to monitor only
every 128th frame (the longest battery saving interval). For
fastest delivery of messages (lowest delivery latency), the
subscriber unit is pre-programmed to monitor every frame. Thus,
battery life and delivery latency can be traded off, depending on
the pager collapse value chosen. In addition, the FLEX.TM. protocol
accommodates a "system collapse" value transmitted at the start of
each frame. The system collapse value affects all subscriber units
in the system. In the event that the system collapse value and the
pager collapse value are different in a given subscriber unit, the
value which causes the subscriber unit to monitor the greater
number of frames per cycle applies.
While the pager collapse value and the system collapse value have
worked reasonably well for providing a pre-programmed trade-off
between battery life and delivery latency and for overcoming
certain queuing imbalances, neither provides a dynamically
adjustable battery saving interval that can be custom tailored for
an individual subscriber unit. A custom tailored, dynamically
adjustable battery saving interval is needed, because events can
occur in the messaging system that can temporarily alter the
optimum trade-off between battery life and delivery latency for a
given subscriber unit.
SUMMARY OF THE INVENTION
An aspect of the present invention is a method of applying a
dynamic adjustment to a battery saving interval utilized for
communicating with a portable subscriber unit in a radio
communication system. The method comprises the steps of observing
an occurrence of a predetermined triggering event associated with
the portable subscriber unit, and adjusting the battery saving
interval utilized for communicating with the portable subscriber
unit in response to the predetermined triggering event, while
leaving battery saving intervals of other portable subscriber units
in the system unchanged.
Another aspect of the present invention is a controller in a radio
communication system for applying a dynamic adjustment to a battery
saving interval utilized for communicating with a portable
subscriber unit. The controller comprises a network interface for
accepting messages from message originators, and a processing
system coupled to the network interface for processing the
messages. The controller further comprises a transceiver interface
coupled to the processing system for transmitting the messages and
for receiving acknowledgments to the messages. The processing
system is programmed to observe an occurrence of a predetermined
triggering event associated with the portable subscriber unit; and
to adjust the battery saving interval utilized for communicating
with the portable subscriber unit in response to the predetermined
triggering event, while leaving battery saving intervals of other
portable subscriber units in the system unchanged.
Another aspect of the present invention is a portable subscriber
unit in a radio communication system for applying a dynamic
adjustment to a battery saving interval utilized for communicating
with a fixed portion of the system. The portable subscriber unit
comprises a receiver for receiving messages from the fixed portion,
and a processing system coupled to the receiver for processing the
messages. The portable subscriber unit further comprises a
transmitter coupled to the processing system for acknowledging the
messages. The processing system is programmed to observe an
occurrence of a predetermined triggering event associated with the
portable subscriber unit; and to adjust the battery saving interval
utilized for communicating with the fixed portion in response to
the predetermined triggering event, while leaving battery saving
intervals of other portable subscriber units in the system
unchanged.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an electrical block diagram of a radio communication
system in accordance with the present invention.
FIG. 2 is an electrical block diagram of portions of a controller
and a base station in accordance with the present invention.
FIG. 3 is an electrical block diagram of a portable subscriber unit
in accordance with the present invention.
FIG. 4 is a protocol diagram in accordance with the present
invention.
FIG. 5 is a flow chart depicting operation of the radio
communication system in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, an electrical block diagram of a radio
communication system in accordance with the present invention
comprises a fixed portion 102 including a controller 112 and a
plurality of base stations 116, and a portable portion including a
plurality of portable subscriber units 122, preferably having
acknowledge-back capability. The base stations 116 are used for
communicating with the portable subscriber units 122 utilizing
conventional radio frequency (RF) techniques, and are coupled by
communication links 114 to the controller 112, which controls the
base stations 116.
The hardware of the controller 112 is preferably a combination of
the Wireless Messaging Gateway (WMG.TM.) Administrator! paging
terminal, and the RF-Conductor!.TM. message distributor
manufactured by Motorola, Inc. The hardware of the base stations
116 is preferably a combination of the Nucleus.RTM. Orchestra!
transmitter and RF-Audience!.TM. receivers manufactured by
Motorola, Inc. It will be appreciated that other similar hardware
can be utilized as well for the controller 112 and the base
stations 116.
Each of the base stations 116 transmits RF signals to the portable
subscriber units 122 via a transceiver antenna 118. The base
stations 116 each receive RF signals from the plurality of portable
subscriber units 122 via the transceiver antenna 118. The RF
signals transmitted by the base stations 116 to the portable
subscriber units 122 (outbound messages) comprise selective call
addresses identifying the portable subscriber units 122, and data
or voice messages originated by a caller. The RF signals
transmitted by the portable subscriber units 122 to the base
stations 116 (inbound messages) comprise responses that include
positive acknowledgments (ACKs), negative acknowledgments (NAKs),
and unscheduled messages. An embodiment of an acknowledge-back
messaging system is described in U.S. Pat. No. 4,875,038 issued
Oct. 17, 1989 to Siwiak et al., which is hereby incorporated herein
by reference.
The controller 112 preferably is coupled by telephone links 101 to
a public switched telephone network (PSTN) 110 for receiving
selective call message originations therefrom. Selective call
originations comprising voice and data messages from the PSTN 110
can be generated, for example, from a conventional telephone 111
coupled to the PSTN 110. It will be appreciated that,
alternatively, other types of communication networks, e.g., packet
switched networks and local area networks, can be utilized as well
for transporting originated messages to the controller 112.
The protocol utilized for outbound and inbound messages is
preferably similar to Motorola's well-known FLEX.TM. family of
digital selective call signaling protocols. These protocols utilize
well-known error detection and error correction techniques and are
therefore tolerant to bit errors occurring during transmission,
provided that the bit errors are not too numerous in any one code
word. It will be appreciated that other suitable two-way protocols
can be used as well.
FIG. 2 is an electrical block diagram 200 of portions of the
controller 112 and the base station 116 in accordance with the
present invention. The controller 112 includes a processing system
210, a transceiver interface 204, and a network interface 218. The
base station 116 includes a base transmitter 206 and at least one
base receiver 207.
The processing system 210 is used for directing operations of the
controller 112. The processing system 210 preferably is coupled
through the transceiver interface 204 to the base transmitter 206
via the communication link 114. The processing system 210
preferably also is coupled through the transceiver interface 204 to
the base receiver 207 via the communication link 114. The
communication link 114 utilizes, for example, conventional means
such as a direct wire line (telephone) link, a data communication
link, or any number of radio frequency links, such as a radio
frequency (RF) transceiver link, a microwave transceiver link, or a
satellite link, just to mention a few. The processing system 210 is
also coupled to the network interface 218 for accepting outbound
messages originated by callers communicating via the PSTN 110
through the telephone links 101.
In order to perform the functions necessary for controlling
operations of the controller 112 and the base stations 116, the
processing system 210 preferably includes a conventional computer
system 212, and a conventional mass storage medium 214. The
conventional mass storage medium 214 includes, for example, a
subscriber database 220, comprising subscriber user information
such as addressing and programming options of the portable
subscriber units 122.
The conventional computer system 212 is preferably programmed by
way of software included in the conventional mass storage medium
214 for performing the operations and features required in
accordance with the present invention. The conventional computer
system 212 preferably comprises a plurality of processors such as
VME Sparc.TM. processors manufactured by Sun Microsystems, Inc.
These processors include memory such as dynamic random access
memory (DRAM), which serves as a temporary memory storage device
for program execution, and scratch pad processing such as, for
example, storing and queuing messages originated by callers using
the PSTN 110, processing acknowledgments received from the portable
subscriber units 122, and protocol processing of messages destined
for the portable subscriber units 122. The conventional mass
storage medium 214 is preferably a conventional hard disk mass
storage device.
It will be appreciated that other types of conventional computer
systems 212 can be utilized, and that additional computer systems
212 and mass storage media 214 of the same or alternative type can
be added as required to handle the processing requirements of the
processing system 210. It will be further appreciated that
additional base receivers 207 either remote from or collocated with
the base transmitter 206 can be utilized to achieve a desired
inbound sensitivity, and that additional, separate antennas 118 can
be utilized for the base transmitter 206 and the base receivers
207. It will be further appreciated that, alternatively, in some
systems the transmitter 206 can be arranged such that it can
transmit a plurality of independent messages on a plurality of
communication channels at the same time.
The mass medium 214 preferably includes software and various
databases utilized in accordance with the present invention. An
occurrence observing element 222 of the mass medium includes
software for observing an occurrence of a predetermined triggering
event associated with the portable subscriber unit 122, as will be
described further below. In addition, a battery saving adjustment
element 224 adjusts a battery saving interval utilized for
communicating with the portable subscriber unit 122 in response to
the predetermined triggering event, as will also be described
further below.
FIG. 3 is an electrical block diagram of the portable subscriber
unit 122 utilized in practicing the present invention. The portable
subscriber unit 122 comprises a transmitter antenna 302 for
transmitting RF signals to the base stations 116, and a receiver
antenna 305 for intercepting RF signals from the base stations 116.
The transmitter antenna 302 is coupled to a conventional RF
transmitter 304. Similarly, the receiver antenna 305 is coupled to
a conventional RF receiver 306. It will be appreciated that,
alternatively, the receiver 306 and transmitter 304 can be coupled
to a single transceiver antenna, which transmits and intercepts RF
signals to and from the base stations 116.
Radio signals received by the RF receiver 306 produce demodulated
information at the output. The demodulated information is coupled
to the input of a processing system 310 for directing operations of
the portable subscriber unit 122, and for processing outbound
messages. Similarly, inbound messages are processed by the
processing system 310 and delivered to the RF transmitter 304 for
transmission to the base stations 116. A conventional power switch
308, coupled to the processing system 310, controls the supply of
power to the RF transmitter 304 and RF receiver 306, thereby
providing a battery saving function in accordance with the present
invention.
To perform the necessary functions of the portable subscriber unit
122, the processing system 310 includes a microprocessor 316, and a
memory 318. The microprocessor 316 is, for example, embodied by the
M68HC08 micro-controller manufactured by Motorola, Inc. The memory
318 preferably includes a conventional read-only memory (ROM) and a
conventional random-access memory (RAM).
The microprocessor 316 is programmed by way of the memory 318 to
process received outbound messages, and in response thereto to
create and format inbound messages. During outbound message
processing, the microprocessor 316 samples the demodulated signal
generated by the RF receiver 306. The microprocessor 316 then
decodes an address in the demodulated data of the outbound message,
compares the decoded address with one or more addresses stored in
the memory 318, and when a match is detected, proceeds to decode
the accompanying message.
Once the microprocessor 316 has processed the message, if the
message was received without more errors than the microprocessor
316 can correct
according to the protocol, then the microprocessor 316 transmits an
acknowledgment (ACK) signal to the fixed portion 102. The
microprocessor 310 then stores the message in the memory 318, and
generates a call alerting signal to alert a user that a message has
been received. The call alerting signal is directed to a
conventional audible or tactile alerting device 322 for generating
an audible or tactile call alerting signal. On the other hand, if
the message was received with more errors than the microprocessor
316 can correct according to the protocol, then the microprocessor
316 transmits a negative acknowledgment (NAK) signal to the fixed
portion 102, so that the fixed portion 102 can resend the
message.
By the use of appropriate functions provided by the user controls
320, the outbound message is recovered from the memory 318, and
displayed on a display 324, e.g., a conventional liquid crystal
display (LCD). Alternatively, when the message is a voice message,
the message is reproduced on a conventional audio circuit (not
shown in FIG. 3) that is included in the portable subscriber unit
122. Preferably, the portable subscriber unit 122 utilizes
components similar to those of the Tenor.TM. and Tango.TM. personal
messaging units manufactured by Motorola, Inc. of Schaumburg Ill.
It will be appreciated that other similar components can be
utilized as well for the portable subscriber unit 122.
In accordance with the present invention, the memory 318 also
includes an occurrence observing element 312 for observing an
occurrence of a predetermined triggering event associated with the
portable subscriber unit 122, as will be described further below.
In addition, a battery saving adjustment element 314 adjusts the
battery saving interval utilized for communicating by the portable
subscriber unit 122 in response to the predetermined triggering
event, as will also be described further below.
Referring to FIG. 4, a protocol diagram in accordance with the
present invention depicts a FLEX.TM. transmission cycle 402
consisting of 128 transmission frames. Also depicted is a first
battery saving operation 404 for a subscriber unit 122 which
monitors the first frame 413 and every subsequent fourth frame 414
of the transmission cycle, while battery saving for a battery
saving interval equal to the duration of the three frames between
the monitored frames. A second battery saving operation 406 is also
depicted in which the subscriber unit 122 monitors the first frame
409 and every alternate frame 410 thereafter, while battery saving
for a battery saving interval equal to the duration of the single
frames between the monitored frames. In accordance with the present
invention, the radio communication system dynamically adjusts the
battery saving interval utilized for communicating with the
portable subscriber unit 122 in response to a predetermined
triggering event, while leaving battery saving intervals of other
portable subscriber units in the system unchanged. For example, the
system can switch between the first and second battery saving
operations 404, 406 in response to the predetermined triggering
event. The ability to switch dynamically between different battery
saving intervals advantageously allows the system to maintain long
battery life while retaining an ability to reduce delivery latency
when required for special events uniquely associated with the
portable subscriber unit 122.
It will be appreciated that in the FLEX.TM. protocol the above
described method of adjusting the battery saving interval can
adjust the interval from a low limit of zero (minimum battery
saving and minimum delivery latency) to a high limit of 127 frames
(maximum battery saving and maximum delivery latency). It will be
further appreciated that for proper operation both the fixed
portion 102 of the system and the portable subscriber unit 122 must
switch their respective battery saving intervals simultaneously in
a coordinated fashion. This is easily accomplished without
additional communication when the triggering event is known to both
the fixed portion 102 and the portable subscriber unit 122.
Alternatively, when the triggering event is known to only one of
the fixed portion 102 and the portable subscriber unit 122, then
the switching of the respective battery saving intervals requires a
message to be transmitted between the fixed portion 102 and the
portable subscriber unit 122 to effect the change.
FIG. 5 is a flow chart 500 depicting operation of the radio
communication system in accordance with the present invention. The
flow chart 500 begins when the system is powered up 502.
Thereafter, whenever the controller 112 and/or the portable
subscriber unit 122 observes 504 an occurrence of a predetermined
triggering event, action is taken to adjust the battery saving
interval utilized for communicating with the portable subscriber
unit 122 in response to the predetermined triggering event, while
leaving battery saving intervals of other portable subscriber units
122 in the system unchanged.
In one embodiment according to the present invention the
predetermined triggering event comprises a presence of a message in
queue for the portable subscriber unit 122, the message having a
length greater than a predetermined length. For example, a message
long enough to require multiple frames 408 for transmission can
trigger a shorter battery saving interval so that the message can
be delivered with less delay. When delivery of the long message is
complete, the battery saving interval is restored to a nominal
value for better battery life. As the portable subscriber unit 122
has no knowledge of the presence of the long message prior to its
transmission, the controller 112 preferably commands the portable
subscriber unit 122 to shorten its battery saving interval prior to
transmission of the message.
In a second embodiment, the predetermined triggering event
comprises a presence of a message in queue for the portable
subscriber unit 122, the message being of a predetermined type. For
example, a voice message can be sent utilizing the nominal battery
saving interval, while an interactive data message is sent
utilizing a shorter battery saving interval. As in the example
above, the controller 112 preferably commands the portable
subscriber unit 122 to shorten its battery saving interval prior to
transmission of the interactive data message.
In a third embodiment, the battery saving interval is adapted by an
amount determined from a call rate experienced by the portable
subscriber unit 122 during a predetermined period. For example, the
call rate of the portable subscriber unit 122 during a
predetermined time period, e.g., the preceding 24 hours, is
monitored by both the controller 112 and the portable subscriber
unit 122. If the call rate exceeds a predetermined value, e.g.,
three calls per hour, then the battery saving interval is
shortened. Otherwise, the battery saving interval remains at the
nominal value. As both the controller 112 and the portable
subscriber unit 122 can compute the call rate of the portable
subscriber unit 122 at some predetermined time, e.g., once every
hour on the hour, no additional communication is required between
the controller 112 and the portable subscriber unit 122 to effect
the change in the battery saving interval.
In a fourth embodiment, the battery saving interval is adapted by
an amount determined from an elapsed time since a last
communication was experienced by the portable subscriber unit 122.
For example, both the controller 112 and the portable subscriber
unit 122 can determine the elapsed time since a last communication
was experienced by the portable subscriber unit 122. Then, when a
message is queued for the portable subscriber unit 122, if the
elapsed time since a prior message was received is less than a
predetermined amount, e.g., fifteen minutes, both the controller
112 and the portable subscriber unit 122 can utilize a shorter
battery saving interval for a subsequent predetermined period,
e.g., the next hour.
In a fifth embodiment, the battery saving interval is adapted by an
amount determined from a user preference entered through a user
control of the portable subscriber unit 122. This feature is
useful, for example, to reduce delivery latency when the user is
expecting an important and urgent message.
In a sixth embodiment the battery saving interval is adapted by an
amount determined from a battery capacity of the portable
subscriber unit 122. For example, the battery saving interval can
be shortened for improved delivery latency when a high-capacity
battery is installed in the portable subscriber unit 122. It will
be appreciated that the battery must be encoded to identify its
capacity to the portable subscriber unit 122, which in turn must
request a shorter battery saving interval from the controller 112.
The battery capacity can be encoded, for example, by the presence
or absence of a mechanical notch in the battery which would be
detected by a micro switch when the battery is installed in the
portable subscriber unit 122.
In a seventh embodiment, the predetermined triggering event occurs
in response to an attempt to send a message to the portable
subscriber unit 122, the message having a message priority. Then,
the battery saving interval is adapted by an amount determined by
the message priority. For example, a message having the highest
priority can cause the utilization of the shortest battery saving
interval in order to minimize the delivery latency.
In an eighth embodiment, the battery saving interval is adapted by
an amount determined by whether or not the portable subscriber unit
122 is connected to an external power source. For example, when the
external power source is connected, the portable subscriber unit
122 can request the controller 112 to switch to the shortest
battery saving interval for best delivery latency, as power
consumption is of little concern. Any of several well known
techniques, e.g., a micro switch closure, electrical contact
closure, etc., can be utilized for determining that the external
power source has been connected.
In a ninth embodiment, the battery saving interval is adapted by an
amount determined by time of day. For example, during the busiest
hours of the day the battery saving interval can be reduced to
shorten delivery latency, while at other times the battery saving
interval is restored to the nominal value to conserve battery
power.
In a tenth embodiment, the predetermined triggering event is a
request from the portable subscriber unit 122 which requires a
response from the fixed portion 102, and the adjusting step
preferably occurs automatically in both the fixed portion 102 and
the portable subscriber unit 122 in response to the request. For
example, the portable subscriber unit 122 can request some
information, e.g., a stock quotation. In response, both the
portable subscriber unit 122 and the fixed portion 102 switch to a
shortened battery saving interval for delivery of the stock
quotation, after which the battery saving interval is restored to
the nominal value.
In an eleventh embodiment, the predetermined triggering event is a
request from the portable subscriber unit 122 which requires a
response from the fixed portion 102, and the step of adjusting the
battery saving interval comprises the step of transmitting a
command from the fixed portion 102 to the portable subscriber unit
122 to complete the adjusting step in response to the request.
In a twelfth embodiment, the battery saving interval has a nominal
value before applying the dynamic adjustment to the battery saving
interval, and the predetermined triggering event is a request from
the portable subscriber unit 122 which requires a response from the
fixed portion 102. In this case, the adjusting step comprises the
step of restoring the battery saving interval to the nominal value
by one of: (a) a time-out after commencing the adjusting step, (b)
a communication of the response, and (c) a command sent between the
fixed portion 102 and the portable subscriber unit 122.
In a thirteenth embodiment, the observing step comprises the step
of detecting a transmission of a negative acknowledgment (NAK) from
the portable subscriber unit 122, and the adjusting step comprises
the step of shortening the battery saving interval in response to
the NAK. In this manner a retry message sent in response to the NAK
advantageously will receive a faster delivery. In this embodiment
the observing step further comprises the step of detecting a
transmission of a positive acknowledgment (ACK) from the portable
subscriber unit 122, and the adjusting step further comprises the
step of restoring the battery saving interval to the nominal value
in response to the ACK. Alternatively, the adjusting step can
further comprise the step of restoring the battery saving interval
to the nominal value a predetermined time after the NAK. In
addition, the retry message is preferably queued in response to the
NAK, such that the retry message is given transmission priority
over non-retry messages in the system. In this embodiment, the step
of shortening the battery saving interval preferably comprises the
step of reducing the battery saving interval to a minimum possible
value, after which a Where aRe You (WRU) command is transmitted to
the portable subscriber unit 122 in a next available transmission
frame. This procedure advantageously allows the location of the
portable subscriber unit 122 to be quickly ascertained so that a
nearby base station 116 can be selected to communicate with the
portable subscriber unit 122.
In a fourteenth embodiment, the triggering event is a command
transmitted to the portable subscriber unit from a fixed portion of
the radio communication system. The command preferably can change
the battery saving interval to a level that is either higher or
lower than the system collapse value transmitted by the radio
communication system. The command preferably can specify a duration
determined by, for example, a time limit, or until further notice,
or when the portable subscriber unit leaves the zone in which it is
currently located. The command can be implemented in the FLEX.TM.
protocol, for example, by creating a new vector, using well-known
techniques. After receiving the command, the portable subscriber
unit adjusts its battery saving interval in accordance with the
command. Alternatively, the command can direct the portable
subscriber unit to disable a currently used address set for a
current battery saving interval and to enable a different address
set for a different battery saving interval.
In a fifteenth embodiment, the battery saving interval of the
portable subscriber unit is set to a new level. This can be done by
a semi-permanent firmware modification in the portable subscriber
unit or, alternatively, by a command from the fixed portion of the
system. After the battery saving interval is set to the new level,
the portable subscriber unit ignores system battery saving
intervals transmitted in the future by the fixed portion of the
radio communication system. This embodiment is particularly useful
to subscriber units which require very long battery saving
intervals, e.g., two-way subscriber units used for reporting water
meter readings. Such units need to communicate with the system only
once every few hours, and thus will benefit from ignoring the
(shorter) system battery saving intervals, which are optimized for
normal message traffic.
In a sixteenth embodiment, the predetermined triggering event is an
application program running in the portable subscriber unit, and
the system and the subscriber unit adjust the battery saving
interval in accordance with the requirements of the application
program. In the event that the system starts and stops the
application program, both the subscriber unit and the fixed portion
are aware of the running of the application program, and can act
accordingly. When the subscriber unit starts and stops the
application program by itself, it must communicate the starting and
stopping thereof to the fixed portion of the system.
It will be appreciated that in the above embodiments adjusting the
battery saving interval includes adjusting at least one of (a) the
battery saving interval utilized for outbound communications to the
portable subscriber unit, i.e., the outbound collapse, and (b) the
battery saving interval utilized for inbound communications from
the portable subscriber unit, i.e., the inbound retry interval for
non-acknowledged inbound messages.
In some of the preceding embodiments, similar information is
present in both the fixed portion 102 of the radio communication
system and in the portable subscriber unit 122. Thus, the steps of
observing the occurrence of the predetermined triggering event and
adjusting the battery saving interval utilized for communicating
with the portable subscriber unit 122 in response to the
predetermined triggering event occur independently in both the
fixed portion 102 and the portable subscriber unit 122 based upon
the similar information present. For such cases no communication is
required between the fixed portion 102 and the portable subscriber
unit 122 to effect the change in the battery saving interval. In
others of the
preceding embodiments, however, the observing step occurs in only
one of the fixed portion 102 and the portable subscriber unit 122,
and a communication is required between the fixed portion 102 and
the portable subscriber unit 122 to accomplish the adjustment of
the battery saving interval.
Thus it should be apparent that the present invention
advantageously provides a dynamically adjustable battery saving
interval that can be custom tailored for an individual subscriber
unit. A custom tailored, dynamically adjustable battery saving
interval is useful and desirable, because events can occur in the
messaging system that can temporarily alter the optimum trade-off
between battery life and delivery latency for a given subscriber
unit.
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